Machine-tool for grinding spherical surfaces.



. G. H. TRUE.

MACHINE TOOL FOP. GRINDING SPHERIOAL SURFACES. APPLIOAT ION FILED MAY 13, 1914.

Patented Feb. 16, 1915.

//v mvron CHARLES H. TRUE I earn 'JL. sick) @HhItLES H. TRUE, 033 HAIi'IlliOND, INDIANA, ASSIGNOR TO LQCGMO'I'IVE COMPANY, OF NEW YORK, N. Y., A CORPORATION OFDELAWARE.

MACHINE-T0033 FOR GRINDING SPHERICAL QURFECES.

Specification of Letters Patent.

Patented Feb. it}, i?

Application filed May 18, 1914:. Serial No. 839,263.

specification.

My invention relates to a machine tool, preferablyportable self-contained and motor driven, for use in. grinding spherical surfaces quickly and accurately.

-While my invention may be applied in the grinding of either convex or concave spherical surfaces, I have, in the preferred form herein disclosed, intended it more particularly for use in grinding the concave spherical surfaces in superheater headers or steam collectors, as they are often called, which receive similarly formed ends of superheater elements, and which constitute the outer ends of the several openings into the header, throusgh which steam is passed to and from said elements. tiuperheater ele ments connected to the header in this way are spoken of as having ball and joint connection. dOll'ltS of this kind are shown,

for example, in the patent to Cole and lrl oifmann, No. 1,054,676, of March .4, 1913.

It is the object of my invention to provide a machine tool of the character specifled which may be readily applied to the header and preferably moved from point to point where the spherical surfaces are to "be ground.

A further object of my invention is to provide a simple and compact tool of the character specified which shall grind the spherical surfaces automatically and accurately and with little if any attention on the part of an attendant after thetool has been placed in position.

A still further object of my invention is to provide a machine tool of the character specifiedwhich shall operate uniformly and produce uniform results.

Further objects of my invention will appear as the specification proceeds.

My invention resides in certain details of construction and arrangement, and will be better understood by referring to the accompanying drawing which illustrates a central longitudinal section, partly in elevation, of a preferred form ofthe invention.

Referring to the drawing, the heavy metal base 1, the lower surface of which is machined accurately flat, is provided with an overhead, rigid standard or bracket 2. Mounted above the base is an. air motor 3 having an extended shaft 42, the two ends of which are journaled respectively in the base and in the bracket 2. Shaft t has a spur gear 5 fixed thereto and meshing with a second spur gear 6, of considerably greater diameter, which isrotatably mounted upon the lower end of a fixed shaft 7 carried at the outer end of the bracket 2. Near the periphcry of gear 6 is boss 8, counterbored to receive a rotatable spindle 9 carrying, at its end, on the upper side of the boss, at small bevel spur gear 10, and at its lower extremity connccting to a sleeve 11 by a preferably universal joint 12. The axis of spindle 9 is inclined inwardly and downwardly so as to intersect the axis of shaft 7 just above the plane of the lower surface of base 1. A bevel gear 13 is fixed, so that it cannot rotate, upon the shaft 7 just above the gear 6 and its diameter is such as to mesh with bevel gear 10.

A spindle 14 is accurately but slidably fitted within the sleeve 11 and provided with a key 15 projecting through a slot 16 in said sleeve; this permits the spindle to slide up and down in the sleeve but compels it to rotate therewith. At the lower end of spindle l lls the grinding element 17, the

extreme tip of which is couvexed spherically, and mounted upon the spindle above this grinding element is weight 18. A ilat sheet metal gage 19 the lower surface of which is substantially flush with the lower surface of base 1, is fixed to said base and provided with a hole 20, the center of which lics'iu the axis of gear 6. The diameter of this hole is slightly greater than the diameterof the spherical surface which is to be ground.

In operation the machine is placed upon the previously machined surface of the header in which are the openings whose ing element 17 in. the countersunk end of the header opening. As the grinding element rotates about spindle 14, the shaft itself will describe a conical surface of revolution about the point at which its axis intersects the axis of gear 6. During the grinding operation the spindle 14=will rise and fall in sleeve 11 in correspondence with any inequality of the surface which is being ground and in accordance with any variation in the rate of grinding due to varying decrease of hardness of the metal itself.

' The weight 18 should be suitably selected so as to cause the metal to be ground away at'a convenient rate.

While I have shown my invention driven by an air motor it is obvious that a gasolene or electric motor or any other desired form of motor might be substituted therefor.

When a suflicient amount of material has been ground away so as to leave a satisfactory spherical surface, the motor is .,stopped and the machine lifted and moved to a point where a second surface is to be ground and'so on until all of the desired spherical surfaces are formed.

Instead of stopping the machine by cutting off the source of power by hand operated switch or the like, I may, of course, arrange to have it stopped automatically by any known form of automatic stop device, of which there are many.

Instead of embodying my invention in a self-contained operable machine as above described, I may, if I prefer, omit the motor altogether and drive gear 6 from any separate and usual source of power by a belt chain or other suitable device.

When the machine is not in use, the

grinding element and its operating shaft, etc., may be ralsed about the universal oint and placed in the metal holding loop or hook21, which is fixed to the bottom of gear 6 diametrically opposite spindle 9.

Other changes of detail may be made within the scope of my invention as defined by the following claims.

I claim':

1. In a tool for grinding spherical surfaces, an inclined shaft, a spherically tipped grinding element flexibly joined to said shaft, and means for rotating said shaft a surface of revolution about an axis which Wlll pass substantially through the center of said grinding element.

3. In a tool for grinding spherical surfaces the combination of a shaft having a fixed axis, a shaft having an axis inclined thereto, a grinding element flexibly joined 'to said inclined shaft, and means operatively relating said two shafts for causing the axis of said inclined shaft to simultaneously describe a conical surface of revolution about the axis of the fixed shaft and to rotate about its own axis.

4:. In-a tool for' grinding spherical sur faces the combination of a main gear, a second gear meshing therewith, a shaft for said second gear having its axis intersecting the axis of the main gear, a grinding element carried by said shaft, and means for rotating said shaft so as to describe a conicalsurface of revolution about the axis of the main gear.

5. In a tool for grinding spherical surfaces the combination of .a' pair of meshed gears having intersecting axes, a shaft fixed to one of said gears, a spherical grinding element flexibly united to said shaft and having its center substantially coincident with the point of intersection of the two axes, and means for moving said shaft sothat its axis will describe a conical surface of revolution about the other axis.

6. In a tool for grinding spherical surfaces, the combination of a fixed and a rotatable gear having a common axis, an outer gear carried by said rotatable gear and meshing with said fixed gear, the axis of said outer ear intersecting the axis of the'first name two gears, a grinding cle-' ment attached to and arranged to rotate with said outer gear and a driving gear meshing with said rotatable gear.

7. A tool for grindin spherical surfaces, comprising a downwardly inclined spindle having a grinding element at its lower end and a universal joint at its upper end, whereby the grinding element is normally partially supported by the Work to be ground and is lowered with the progress of the grinding, and'means for rotating said grinding element upon said spindle while at the same time causing the axis of said spindle to describe a conical surface of revolution about an axis passing through Said grinding element.

In testimony whereof I have hereunto set my hand in the presence of two subscribing witnesses.

CHARLES H. TRUE.

Witnesses:

JAMES J. PHILLIPS, KATE EMERY. 

